Obama, accused by many US lawmakers of failing to explain US objectives in Libya, used his weekly radio and Web address to speak about his Libyan policy and plans on Monday night address to the American people to explain it further.

So far, polls show Americans back the president for using US air power and cruise missiles to attack Libyan leader Muammar Qaddafi's air defence and other targets aimed at supporting Libyan rebels and protecting civilians from government forces.

A Reuters-Ipsos poll in recent days said 60 percent of Americans back him on Libya, although only 17 percent saw him as a strong and decisive leader.

A Gallup poll put American support for his Libyan move at 47 percent, with 37 percent disapproving.

"We're succeeding in our mission," Obama said.

"Because we acted quickly, a humanitarian catastrophe has been avoided and the lives of countless civilians innocent men, women and children have been saved."

Easing some pressure on Obama, NATO is expected to take over command and control of the week old allied military operation this weekend from the United States.

"Our military has provided unique capabilities at the beginning, but this is now a broad, international effort," he said, noting that Arab partners like Qatar and the United Arab Emirates have committed aircraft.

Obama was cautious on the potential for US intervention elsewhere, as Americans now see news reports of unrest convulsing Syria and Yemen.

"As commander in chief, I face no greater decision than sending our military men and women into harm's way.

And the United States should not and cannot intervene every time there's a crisis somewhere in the world," he said.